1. Technical Field
This invention relates in general to telecommunications and, more particularly, to a telecommunications receiver with automatic gain control.
2. Description of the Related Art
In a radio frequency receiver, an automatic gain control circuit is often used to compensate for variations in signal strength of the received signal. Variations in the signal strength of the received signal can occur for various reasons, such as changes in transmission distances, atmospheric conditions, changes in channels, obstructions in the transmission path, and so on.
Accordingly, automatic gain control circuits are used to maintain a relatively stable output signal volume, despite varying input signal strength. Current solutions base gain adjustment decisions on a signal level measurement performed in a digital signal processor (DSP) after digital channel filtering has been applied to the input signal. As a result, saturation may occur in the analog-to-digital converter (ADC) which translates the input signal (where the signal may be the superposition of the useful signal, DC offset, adjacent channels and blockers) to a digital signal for processing by the DSP. When saturation occurs, signal information is irretrievably lost.
Therefore, a need has arisen for a radio receiver with automatic gain control that avoids ADC saturation.